Use icon buttons

[jdorn]

The buttons in JSON Editor are all text right now and can get really long (especially in the table editor). We should use icon buttons instead of text buttons when possible.

Add the following initialization option:

• icons - The type of icons to use. Default to false. If set to a supported icon library, display only icons for buttons and not text. Only use the text for the title attribute.

Add a $.jsoneditor.icons property to override the default.

Create a $.jsoneditor.AbstractIconTheme class with methods like getMoveDownIcon.

Support the following icon libraries:

• fontawesome3
• fontawesome4
• foundation2
• foundation3
• bootstrap2
• bootstrap3
• symbolset
• jqueryui

Add a parameter to the theme methods getButton and setButtonText to accept an icon.

[jdorn]

Added all icon libraries except for "symbolset" since it's not open source and doesn't have 1 definitive list of icons.